Fuel524

i understand how motors work and how the exhaust works as i assume most of us here do. but does ths same apply to a rotary? in comparison with a boinger. lets say on a stock exhaust(rotary) emptying the cats will this decrease hp or increase? no lets say on an unpgraded exhaust the whole **** headers n back if you have cats will that decrease what the point is of having an upgraded exhaust or just restrict. what i think im getting at is if i have lets say7 RB headers on a stock exhaust with no cats is my immediate flow going to be useless since i havent eliminated the rest of the flow or will it still give me a better exhaust flow. also would most agree that the louder is better??? hp wise that is?in other words is backpressure more necessary on a rotary than a boinger n/a ?

comradegiant

No. Back pressure is not nearly as important on a rotary as on a boinger n/a. You still need some, but not nearly as much since you have no valves to crack.

faye x7

Oh god there are gobs of thread son this stuff and novels written here. Just do a search and you'll find PLENTY of info. heh

Manntis

I must disagree. Proper exhaust pulse tuning is essential for scavenging.

fatboy7

I must concur. Backpressure is evil, you need absolutely none. Scavenging is good, the more the merrier, especially on rotaries.

So you need larger pipes than stock, but since velocity is the key to scavenging, and smaller pipes increase the velocity, you don't want to go too big.